Weather in Florence, Italy
The climate in Florence still remains seasonal. From May the temperartures start to climb towards the mid-60s, which is followed in June (really the most pleasant month to visit) by temperatures that peak in the 70s. Come July and by 11am the temperature is in the late 80s, and as for August, apart from the occasional shower, expect temperatures in the 90s but with the humidity making it feel as though its in the 100s.
A large proportion of Italian's still take their annual holidays in this period, which means you'll find quite a lot of places closed in August too. September and October are also good months to visit, as the bulk of tourists will have left and the temperatures are still in the 70s.
In November and December the temperatures drop, and if we're lucky, snow will be deposited on the Apennine range of mountains nearby.
January, February and March tend to be grey and wet months (particularly March) but finish in April with the Tuscan countryside being turned into rich green paradise (in stark contrast to the burnt and browned landscape of the summer months).